1. Field of the Invention
The present invention relates to liquid crystal display (LCD) devices, and more particularly, to a patterning method for an LCD device.
2. Discussion of the Related Art
Among various ultra-thin flat type display devices, which include a display screen having a thickness of no more than several centimeters, liquid crystal display (LCD) devices are widely used for notebook computers, monitors, aircraft, etc. because they have advantages such as low power consumption and portability.
An LCD device includes lower and upper substrates facing each other at a predetermined interval therebetween, and a liquid crystal layer formed between the lower and upper substrates.
The lower substrate includes a gate line, a data line, and a thin film transistor. The gate line is formed perpendicular to the data line to define a unit pixel region. The thin film transistor is formed adjacent to a crossing of the gate and data lines and serves as a switching device. A pixel electrode is connected to the thin film transistor.
The upper substrate includes a black matrix layer for shielding the gate line, the data line and the thin film transistor from light, a color filter layer formed on the black matrix layer, and a common electrode formed on the color filter layer.
The above-described LCD device includes various elements formed by repeated steps. Photolithography may be used to form the elements in various shapes.
A patterning method using a photolithographic process of the related art will be described with reference to FIGS. 1A to 1C.
FIGS. 1A to 1C are cross sectional views illustrating a patterning method using a photolithography of the related art.
As shown in FIG. 1A, a pattern material layer 20 is formed on a substrate 10, and a layer of photoresist 21 is formed on the pattern material layer 20.
As shown in FIG. 1B, a mask 30 with a predetermined pattern is positioned above the photoresist layer 21, and then light is provided to the substrate 10 by an exposure apparatus.
As shown in FIG. 1C, the photoresist layer 21 is patterned using a development process. The pattern material layer 20 is etched using the patterned photoresist layer 21 as a mask, to obtain a desired pattern 20a. 
The above photolithographic process uses a photoresist layer and a mask with the predetermined pattern that increases the manufacturing cost for an LCD device. In addition, photolithography requires exposure and development, which are complicated processes that increase the manufacturing time of LCD devices.
To overcome these problems associated with photolithography, new patterning methods has been developed using a printing method using a printing roller.
A patterning method using a printing roller according to the related art will be described with reference to the FIGS. 2A to 2D.
FIGS. 2A to 2D are cross sectional views illustrating a process for forming a pattern material layer on a substrate with a printing roller according to the related art.
As shown in FIG. 2A, a pattern material 20 is coated onto a printing plate 40 having recesses and lands.
As shown in FIG. 2B, a blade 35 is used to remove pattern material 20b from the surface of the printing plate 40, leaving pattern material 20a in the recesses of the printing plate 40.
As shown in FIG. 2C, a printing roller 50 is rolled across the printing plate 40. The pattern material 20a remaining in the recesses is printed onto the printing roller 50, forming a predetermined pattern on the printing roller 50.
Referring to FIG. 2D, by rolling the printing roller 50 having the pattern material 20a coated thereonto on a substrate 10, the pattern material 20a of the printing roller 50 is printed onto the substrate 10.
The patterning method using the printing roller and the printing plate does not require a mask having a predetermined pattern, and does not require exposure or development processes, thereby decreasing the manufacturing cost and time.
However, the patterning method using the printing roller according to the related art has the following disadvantages.
In the pattering method using the printing roller and the printing plate according to the related art, as shown in FIG. 2B, the pattern material 20 is coated onto the printing plate 40, and the pattern material 20b is removed from the surface of the printing plate using a blade 35 to leave the pattern material only in the recesses of the printing plate 40. The removal of pattern material 20b from the surface of the printing plate may be incomplete, leaving residue in the portions of the printing plate other than the recesses. The pattern material left in the recesses may be non-uniform. Further, applying the pattern material 20b to the printing plate and then removing portions of the pattern material from the printing plate increases manufacturing cost due to the waste of pattern material.